It is well known that compressed gases, including air, generally contain some moisture. This moisture occurs in compressed air as a natural result of the air being compressed and due to other causes such as the formation of condensation in the interior of a compressed air storage tank. One application in which the presence of moisture in compressed air is particularly undesirable is when such air is being utilized to pressurize truck or automobile tires. The moisture contained in compressed air is corrosive to the steel rims upon which tires are often mounted. Over time, this corrosion may cause leaks between the rim and the bead of the tire, and may weaken the rim itself. Additionally, the rust formed may flake off of the steel rim and collect in the interior of the tire. These rust flakes may clog the tire valve stem and also may abrade the lining of the tire. Such corrosion often requires the tire to be removed from the rim so that the rim can be cleaned and repainted. The moisture contained within tires is also destructive to the steel belts found in an increasing majority of tires. Over time, the steel belts corrode and weaken which may cause a failure of the tire before the tread life has been exhausted.
Prior moisture filters have been designed to be relatively permanently installed in-line to remove moisture from compressed air. In-line moisture filters are not commonly installed and are typically utilized only by those owning specialty systems for compressing air in a laboratory or manufacturing environment. Compressed air systems as are typically found at a gas station or truck service area ordinarily have no such filter. One in need of compressed air to pressurize a "flat" tire generally must use whatever source of compressed air is available and is not able to search for a source which employs an in-line filter.
The moisture contained in compressed air can also be destructive to tools powered by compressed air. Such tools, such as pneumatic impact wrenches can become internally corroded and their usefulness can be reduced or destroyed.